Carboy sanitizing

So I got two 5gal glass carboys today for free. They originally contained sulfuric acid, so I've washed them out and put a sanitizing solution in them filled to the rim overnight. Since sulfuric acid is water soluble the cleaning they are getting will do just fine but is there such thing as food grade glass and if so how do you know what your piece is. They each have a number #2 on the bottoms.

Personally, I have never heard of "food grade glass", only food grade plastics. I think most glass receptacles that are well cleaned and sanitized should be adequate for fermenting beer. As for the sulfuric acid issue, diluting the glass with water and sanitizer should do the job, but to be on the safe side, I would rinse the carboy with a fair amount baking soda and water to ensure that any acid will be neutralized- if the acid stored in the carboys had a high concentration of acid, it may still cause an acidic environment even after a couple of rinsings. Just my $0.02

I didn’t think that such a thing existed (food grade glass) but the glass has a number #2 on the bottom so threw me a curve. I know plastic is numbered but never saw glass. I'm giving it a 24 hour soak with sanitizer and do plan on a rinse or two with baking soda. Thanks for the input.

Typically in the labs I worked in 5 volumes of fresh flush was required to clean vessels.
-David